MKIII MAFT setup: either too lean or fuel cut, need help

[20pwns]

Went down to the dyno today and got sad results. I'm running stock 440’s with MAFT and when we tune to safe A/F levels (11.4 to 11.8), I'm hitting fuel cut at 9 psi...?! When we try to tune out the fuel cut we're getting scary numbers like 13.5 AFR @ 4500 rpm!! We even tried lowering the injector size to 420cc (BASE = 0) and still fuel cuts like crazy... For the heck of it even tried limiting the Hz: Normal, 1500, 1450, 1400... Nope, just nothing works. Once we even hit fuel cut at 1200 Hz!? What the hell?! I heard that once our cars switch to open loop we should be seeing some really rich numbers like in the 9's and 10's but I'm nowhere near those numbers.

What can it be? What do you think is wrong? My base settings are: AUX = 0, BASE = 2, IDLE = 0, MID = 1, WOT = 2. And my fine tune settings are: 3000 = 3, 4000 = 3, 5500 = 0, 6500 = 0. I didn't even get to tune the 5500 and 6500 rpm range because I keep hitting fuel cut before 4500 rpm, very sad... I heard that with the MAFT people are able to run 14.5 psi comfortably with stock fuel system because once on WOT, our cars run so rich that people need to SUBTRACT a lot fuel. Well, I'm nowhere close... I'm having to ADD fuel 'cuz it's so lean and once I do, I'm hitting fuel cut at something stupid like 9 to 10 psi, lol. Geez, this is frustrating, please help. Thanks,

For reference my mods are: Upgraded IC and hard pipes, ball & spring type MBC set to 14 psi, full 3" turbo-back exhaust, MHG, SSQV BOV, MAFT & S-AFC II (not being used, will use to fine tune after MAFT is properly set).

p.s. I haven’t changed the fuel pump but I’ve changed the filter 2 years ago. Other than that, my fuel system is totally OEM. Thanks,

 

[cnewingham]

if its the orig. maft good luck. I could never get my a/f's at a consistant level. My advise is to ditch it and get the maft-pro, or map-ecu.

 

[20pwns]

Thanks for the advice but I don't think I'll do that just yet. I just got the unit... And I already know a few locals running the same setup and they are doing fine so to say that the MAFT flat out sucks isn't a fair statement. Thanks though.

Is there anyone else with ideas other than to "ditch" the MAFT?

 

[robbo185]

hmm that is wierd....i have a maft unit and i dont hit fuel cut till 12 psi and i have it on stock settings. I tuned it with an safcII though. try leaving your settings at zero and tune with the SAFCII and see how that goes. Also did you zero out your safc settings when tuning the maft? When I get my wideband installed next week i was gonna mess with the mafts fuel cut settings and if i have safe a/f ratiill get back to you on that to see if maybe its just your maft setting

edit** i had to dump more fuel in with stock injectors...like +33 on my safc at 4300 rpm or so.....most people subtract because they add 550's

 

[20pwns]

try leaving your settings at zero and tune with the SAFCII...

Tried that but same thing. The problem for me is that I'm not seeing enough fuel under WOT where in most cases there should be plenty even from 440's. And because there is so much fuel people generally pull some out and that's what "raises" the fuel cut. There isn't a separate function to adjust the fuel cut in the MAFT.

Also did you zero out your safc settings when tuning the maft?

Yes.

Thanks for the reply!

Anyone else?

 

[90T04]

I had great success with the MAFT. With 550's my fuel cut was over 20psi, I never got there. Are you running in blow through or suck through?

I ran mine in blow through mode, dont know if that makes any difference. I was also using an aeromotive FPR, and higher than stock base FP.

If you are running the MAF in suck through mode, you might want to check for boost leaks. Could be the metered air isnt getting to the engine and still causing fuel cut.

hope this helps
Ryan

 

[robbo185]

what kind of mbc do you have because some are known to spike....i see that you have it set to 14psi...so either you could be spiking, you have a boost leak...or your boost gauge could be off. what kind of gauge do you have?

also if you are on stock fuel pump...that may be the problem because it may be on its way out and not able to supply the fuel your telling it to.

 

[hottscennessey]

I've run over 22 PSI on my SP61GT and 550s. I don't hit fuel cut. You need to try a different base setting and/or up the fuel pressure and re-tune to raise fuel cut. Don't listen to those who say ditch the MAFT, its a great tuning device I tune with MAFT alone and it works great for everything, it even controls my fuel for my alcohol injection.

 

[cnewingham]

to say that the MAFT flat out sucks isn't a fair statement.

I never said that it flat out sucks. Keep an eye on your wideband at all times and you will see what I mean. Maybe I had an issue somewhere else but I tuned with the maft to a base level and then used my safc II to fine tune. The a/f's were in a safe range but looked like the damn ocean waves and could never get it to a consistant number. Then again piggy back on top of another piggyback is not the greatest combination. Do you have a WB in your car? If not I would suggest that be your next addition so you can tune on the street. I got 307 rwhp with mine on stock fuel system and turbo so yes it does work but there are better options is all I was trying to get at.

 

[20pwns]

UPDATE: MAJOR FINDING.

At the beginning of this year I had my engine rebuilt by a local mechanic shop. I've had many problems with my car after the rebuild due to their sloppiness in putting the engine back together: i.e. forgetting to tighten screws and bolts, installing parts that were kicking around in the shop that never originally came from my car, etc...

Well, check this out...

Here is the bolt they put in:

And here is where it was found:

Does your bolt look like this? Or is mine looking really restrictive?! I mean look at the size of the hole down the middle of that bolt?! Can someone double check, please!

 

[20pwns]

In case some of you are wondering what made me look into that bolt, here is the full story:
After I got my car back from the shop I started smelling a lot of fuel in the cabin. Under the hood I found a fuel pressure regulator with a small hole on the top where fuel was shooting out!! When I took the car back and complained about how they overlooked such thing they said, "It wasn't like that when it left here, it must've happened after." And then they told me to go find the replacement part for it. From then on I was on a wild goose chase for days until I found a diagram of the fuel system in the EPC (thanks Cygnus) and I realized that there was no such part for my vehicle; it was supposed to be a damn banjo bolt!!! I was just pissed. When I went back and told them that the damn part never belonged in my car, guess what they told me, "Nope, we put everything back to the way it was. Some other mechanic before us must've put it in there, not us." I was really, really disgusted and mad but saw that there was no point in arguing with these monkeys; they'll never own up and accept the fact that "they" screwed up. So, I asked them to find the right part (the banjo bolt) and put it in, and they did. Or so I thought until today when I went to the dyno and saw that my car was just absolutely freakin' lean!!! The bolt didn't cross my mind at first. I just thought that we were doing something wrong with the tuning but after hours of trying we (the tuner and I) started thinking about other possibilities such as an old fuel filter, fuel pump, etc. and that's when it hit me, the fu*kin’ bolt!!! Could it be?!! I came home from an unsuccessful tune and quickly looked into the bolt. And what do you know... Those fu*kers managed to screw me over again. I'll find out for sure tomorrow when I get the correct part from Toyota but I'm pretty positive that the hole down the middle of that bolt is ridiculously small. So, that's my story, thanks for listening. What do you guys think?

BTW, for 604 folks, the name of the shop is called ATEB, in Burnaby. There, I finally said it. I didn't want to badmouth a business unless I have good reason to but I think this is a good enough reason. So, what ever you do DON'T TAKE YOUR CAR THERE!!!!

 

[pimptrizkit]

yeah i thought i remember you could almost put a pencile into the hole in that thing..



as a mechanic, i can admit some times it's hard to remember where all the bolts go , exspecaily when you take apart an engine. but to mix parts up from other makes or modles, that is just lazy and unprofessional .

i wouldn't send an oil change to a shop like that... seems like their laking on customer service aswell, bet they have alot of comebacks..

 

[hottscennessey]

thats very poor customer service, I'm with pimp.. that doesnt look like the right bolt to me at all. It had a bigger hole, and it didnt look that clean. lol.